This was announced a while ago, and it's just now going into effect:

> The company is implementing its long-lasting promise revealed in 2024, with the option for users to purchase additional play time as needed.

There's also some rollover between months (up to 15 hours)[1].

Previously:

https://news.ycombinator.com/item?id=42078726

https://news.ycombinator.com/item?id=42085089

https://news.ycombinator.com/item?id=42090845

1: https://blogs.nvidia.com/blog/geforce-now-thursday-performan...